the very few times you want the source to something to debug it etc. you'll have a hard time. the 99% of the time when you want not the implementation details b

the very few times you want the source to something to debug it etc. you'll have a hard time. the 99% of the time when you want not the implementation details but some semantically meaningful mapping of one token to one concept, macros are wonderful. another huge benefit is that they take care of fiddly bookkeeping for you - if you have to remember some incantation that involves doing several steps in sequence and making sure that if you change place A you need to change B and C in certain ways, just write a macro and be happy.